Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
[ source navigation ] [ diff markup ] [ identifier search ] [ freetext search ] [ file search ] [ list types ] [ track identifier ]
FreeBSD/Linux Kernel Cross Reference
sys/vm/vm_fault.c
Version:
- FREEBSD - FREEBSD-13-STABLE - FREEBSD-13-0 - FREEBSD-12-STABLE - FREEBSD-12-0 - FREEBSD-11-STABLE - FREEBSD-11-0 - FREEBSD-10-STABLE - FREEBSD-10-0 - FREEBSD-9-STABLE - FREEBSD-9-0 - FREEBSD-8-STABLE - FREEBSD-8-0 - FREEBSD-7-STABLE - FREEBSD-7-0 - FREEBSD-6-STABLE - FREEBSD-6-0 - FREEBSD-5-STABLE - FREEBSD-5-0 - FREEBSD-4-STABLE - FREEBSD-3-STABLE - FREEBSD22 - l41 - OPENBSD - linux-2.6 - MK84 - PLAN9 - xnu-8792
SearchContext: - none - 3 - 10
SearchContext: - none - 3 - 10
1 /*- 2 * Copyright (c) 1991, 1993 3 * The Regents of the University of California. All rights reserved. 4 * Copyright (c) 1994 John S. Dyson 5 * All rights reserved. 6 * Copyright (c) 1994 David Greenman 7 * All rights reserved. 8 * 9 * 10 * This code is derived from software contributed to Berkeley by 11 * The Mach Operating System project at Carnegie-Mellon University. 12 * 13 * Redistribution and use in source and binary forms, with or without 14 * modification, are permitted provided that the following conditions 15 * are met: 16 * 1. Redistributions of source code must retain the above copyright 17 * notice, this list of conditions and the following disclaimer. 18 * 2. Redistributions in binary form must reproduce the above copyright 19 * notice, this list of conditions and the following disclaimer in the 20 * documentation and/or other materials provided with the distribution. 21 * 3. All advertising materials mentioning features or use of this software 22 * must display the following acknowledgement: 23 * This product includes software developed by the University of 24 * California, Berkeley and its contributors. 25 * 4. Neither the name of the University nor the names of its contributors 26 * may be used to endorse or promote products derived from this software 27 * without specific prior written permission. 28 * 29 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 30 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 31 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 32 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 33 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 34 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 35 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 36 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 37 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 38 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 39 * SUCH DAMAGE. 40 * 41 * from: @(#)vm_fault.c 8.4 (Berkeley) 1/12/94 42 * 43 * 44 * Copyright (c) 1987, 1990 Carnegie-Mellon University. 45 * All rights reserved. 46 * 47 * Authors: Avadis Tevanian, Jr., Michael Wayne Young 48 * 49 * Permission to use, copy, modify and distribute this software and 50 * its documentation is hereby granted, provided that both the copyright 51 * notice and this permission notice appear in all copies of the 52 * software, derivative works or modified versions, and any portions 53 * thereof, and that both notices appear in supporting documentation. 54 * 55 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS" 56 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND 57 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE. 58 * 59 * Carnegie Mellon requests users of this software to return to 60 * 61 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU 62 * School of Computer Science 63 * Carnegie Mellon University 64 * Pittsburgh PA 15213-3890 65 * 66 * any improvements or extensions that they make and grant Carnegie the 67 * rights to redistribute these changes. 68 */ 69 70 /* 71 * Page fault handling module. 72 */ 73 74 #include <sys/cdefs.h> 75 __FBSDID("$FreeBSD: releng/10.0/sys/vm/vm_fault.c 255608 2013-09-16 06:25:54Z kib $"); 76 77 #include "opt_ktrace.h" 78 #include "opt_vm.h" 79 80 #include <sys/param.h> 81 #include <sys/systm.h> 82 #include <sys/kernel.h> 83 #include <sys/lock.h> 84 #include <sys/proc.h> 85 #include <sys/resourcevar.h> 86 #include <sys/rwlock.h> 87 #include <sys/sysctl.h> 88 #include <sys/vmmeter.h> 89 #include <sys/vnode.h> 90 #ifdef KTRACE 91 #include <sys/ktrace.h> 92 #endif 93 94 #include <vm/vm.h> 95 #include <vm/vm_param.h> 96 #include <vm/pmap.h> 97 #include <vm/vm_map.h> 98 #include <vm/vm_object.h> 99 #include <vm/vm_page.h> 100 #include <vm/vm_pageout.h> 101 #include <vm/vm_kern.h> 102 #include <vm/vm_pager.h> 103 #include <vm/vm_extern.h> 104 105 #define PFBAK 4 106 #define PFFOR 4 107 #define PAGEORDER_SIZE (PFBAK+PFFOR) 108 109 static int prefault_pageorder[] = { 110 -1 * PAGE_SIZE, 1 * PAGE_SIZE, 111 -2 * PAGE_SIZE, 2 * PAGE_SIZE, 112 -3 * PAGE_SIZE, 3 * PAGE_SIZE, 113 -4 * PAGE_SIZE, 4 * PAGE_SIZE 114 }; 115 116 static int vm_fault_additional_pages(vm_page_t, int, int, vm_page_t *, int *); 117 static void vm_fault_prefault(pmap_t, vm_offset_t, vm_map_entry_t); 118 119 #define VM_FAULT_READ_BEHIND 8 120 #define VM_FAULT_READ_MAX (1 + VM_FAULT_READ_AHEAD_MAX) 121 #define VM_FAULT_NINCR (VM_FAULT_READ_MAX / VM_FAULT_READ_BEHIND) 122 #define VM_FAULT_SUM (VM_FAULT_NINCR * (VM_FAULT_NINCR + 1) / 2) 123 #define VM_FAULT_CACHE_BEHIND (VM_FAULT_READ_BEHIND * VM_FAULT_SUM) 124 125 struct faultstate { 126 vm_page_t m; 127 vm_object_t object; 128 vm_pindex_t pindex; 129 vm_page_t first_m; 130 vm_object_t first_object; 131 vm_pindex_t first_pindex; 132 vm_map_t map; 133 vm_map_entry_t entry; 134 int lookup_still_valid; 135 struct vnode *vp; 136 }; 137 138 static void vm_fault_cache_behind(const struct faultstate *fs, int distance); 139 140 static inline void 141 release_page(struct faultstate *fs) 142 { 143 144 vm_page_xunbusy(fs->m); 145 vm_page_lock(fs->m); 146 vm_page_deactivate(fs->m); 147 vm_page_unlock(fs->m); 148 fs->m = NULL; 149 } 150 151 static inline void 152 unlock_map(struct faultstate *fs) 153 { 154 155 if (fs->lookup_still_valid) { 156 vm_map_lookup_done(fs->map, fs->entry); 157 fs->lookup_still_valid = FALSE; 158 } 159 } 160 161 static void 162 unlock_and_deallocate(struct faultstate *fs) 163 { 164 165 vm_object_pip_wakeup(fs->object); 166 VM_OBJECT_WUNLOCK(fs->object); 167 if (fs->object != fs->first_object) { 168 VM_OBJECT_WLOCK(fs->first_object); 169 vm_page_lock(fs->first_m); 170 vm_page_free(fs->first_m); 171 vm_page_unlock(fs->first_m); 172 vm_object_pip_wakeup(fs->first_object); 173 VM_OBJECT_WUNLOCK(fs->first_object); 174 fs->first_m = NULL; 175 } 176 vm_object_deallocate(fs->first_object); 177 unlock_map(fs); 178 if (fs->vp != NULL) { 179 vput(fs->vp); 180 fs->vp = NULL; 181 } 182 } 183 184 /* 185 * TRYPAGER - used by vm_fault to calculate whether the pager for the 186 * current object *might* contain the page. 187 * 188 * default objects are zero-fill, there is no real pager. 189 */ 190 #define TRYPAGER (fs.object->type != OBJT_DEFAULT && \ 191 ((fault_flags & VM_FAULT_CHANGE_WIRING) == 0 || wired)) 192 193 /* 194 * vm_fault: 195 * 196 * Handle a page fault occurring at the given address, 197 * requiring the given permissions, in the map specified. 198 * If successful, the page is inserted into the 199 * associated physical map. 200 * 201 * NOTE: the given address should be truncated to the 202 * proper page address. 203 * 204 * KERN_SUCCESS is returned if the page fault is handled; otherwise, 205 * a standard error specifying why the fault is fatal is returned. 206 * 207 * The map in question must be referenced, and remains so. 208 * Caller may hold no locks. 209 */ 210 int 211 vm_fault(vm_map_t map, vm_offset_t vaddr, vm_prot_t fault_type, 212 int fault_flags) 213 { 214 struct thread *td; 215 int result; 216 217 td = curthread; 218 if ((td->td_pflags & TDP_NOFAULTING) != 0) 219 return (KERN_PROTECTION_FAILURE); 220 #ifdef KTRACE 221 if (map != kernel_map && KTRPOINT(td, KTR_FAULT)) 222 ktrfault(vaddr, fault_type); 223 #endif 224 result = vm_fault_hold(map, trunc_page(vaddr), fault_type, fault_flags, 225 NULL); 226 #ifdef KTRACE 227 if (map != kernel_map && KTRPOINT(td, KTR_FAULTEND)) 228 ktrfaultend(result); 229 #endif 230 return (result); 231 } 232 233 int 234 vm_fault_hold(vm_map_t map, vm_offset_t vaddr, vm_prot_t fault_type, 235 int fault_flags, vm_page_t *m_hold) 236 { 237 vm_prot_t prot; 238 long ahead, behind; 239 int alloc_req, era, faultcount, nera, reqpage, result; 240 boolean_t growstack, is_first_object_locked, wired; 241 int map_generation; 242 vm_object_t next_object; 243 vm_page_t marray[VM_FAULT_READ_MAX]; 244 int hardfault; 245 struct faultstate fs; 246 struct vnode *vp; 247 int locked, error; 248 249 hardfault = 0; 250 growstack = TRUE; 251 PCPU_INC(cnt.v_vm_faults); 252 fs.vp = NULL; 253 faultcount = reqpage = 0; 254 255 RetryFault:; 256 257 /* 258 * Find the backing store object and offset into it to begin the 259 * search. 260 */ 261 fs.map = map; 262 result = vm_map_lookup(&fs.map, vaddr, fault_type, &fs.entry, 263 &fs.first_object, &fs.first_pindex, &prot, &wired); 264 if (result != KERN_SUCCESS) { 265 if (growstack && result == KERN_INVALID_ADDRESS && 266 map != kernel_map) { 267 result = vm_map_growstack(curproc, vaddr); 268 if (result != KERN_SUCCESS) 269 return (KERN_FAILURE); 270 growstack = FALSE; 271 goto RetryFault; 272 } 273 return (result); 274 } 275 276 map_generation = fs.map->timestamp; 277 278 if (fs.entry->eflags & MAP_ENTRY_NOFAULT) { 279 panic("vm_fault: fault on nofault entry, addr: %lx", 280 (u_long)vaddr); 281 } 282 283 if (fs.entry->eflags & MAP_ENTRY_IN_TRANSITION && 284 fs.entry->wiring_thread != curthread) { 285 vm_map_unlock_read(fs.map); 286 vm_map_lock(fs.map); 287 if (vm_map_lookup_entry(fs.map, vaddr, &fs.entry) && 288 (fs.entry->eflags & MAP_ENTRY_IN_TRANSITION)) { 289 fs.entry->eflags |= MAP_ENTRY_NEEDS_WAKEUP; 290 vm_map_unlock_and_wait(fs.map, 0); 291 } else 292 vm_map_unlock(fs.map); 293 goto RetryFault; 294 } 295 296 /* 297 * Make a reference to this object to prevent its disposal while we 298 * are messing with it. Once we have the reference, the map is free 299 * to be diddled. Since objects reference their shadows (and copies), 300 * they will stay around as well. 301 * 302 * Bump the paging-in-progress count to prevent size changes (e.g. 303 * truncation operations) during I/O. This must be done after 304 * obtaining the vnode lock in order to avoid possible deadlocks. 305 */ 306 VM_OBJECT_WLOCK(fs.first_object); 307 vm_object_reference_locked(fs.first_object); 308 vm_object_pip_add(fs.first_object, 1); 309 310 fs.lookup_still_valid = TRUE; 311 312 if (wired) 313 fault_type = prot | (fault_type & VM_PROT_COPY); 314 315 fs.first_m = NULL; 316 317 /* 318 * Search for the page at object/offset. 319 */ 320 fs.object = fs.first_object; 321 fs.pindex = fs.first_pindex; 322 while (TRUE) { 323 /* 324 * If the object is dead, we stop here 325 */ 326 if (fs.object->flags & OBJ_DEAD) { 327 unlock_and_deallocate(&fs); 328 return (KERN_PROTECTION_FAILURE); 329 } 330 331 /* 332 * See if page is resident 333 */ 334 fs.m = vm_page_lookup(fs.object, fs.pindex); 335 if (fs.m != NULL) { 336 /* 337 * Wait/Retry if the page is busy. We have to do this 338 * if the page is either exclusive or shared busy 339 * because the vm_pager may be using read busy for 340 * pageouts (and even pageins if it is the vnode 341 * pager), and we could end up trying to pagein and 342 * pageout the same page simultaneously. 343 * 344 * We can theoretically allow the busy case on a read 345 * fault if the page is marked valid, but since such 346 * pages are typically already pmap'd, putting that 347 * special case in might be more effort then it is 348 * worth. We cannot under any circumstances mess 349 * around with a shared busied page except, perhaps, 350 * to pmap it. 351 */ 352 if (vm_page_busied(fs.m)) { 353 /* 354 * Reference the page before unlocking and 355 * sleeping so that the page daemon is less 356 * likely to reclaim it. 357 */ 358 vm_page_aflag_set(fs.m, PGA_REFERENCED); 359 if (fs.object != fs.first_object) { 360 if (!VM_OBJECT_TRYWLOCK( 361 fs.first_object)) { 362 VM_OBJECT_WUNLOCK(fs.object); 363 VM_OBJECT_WLOCK(fs.first_object); 364 VM_OBJECT_WLOCK(fs.object); 365 } 366 vm_page_lock(fs.first_m); 367 vm_page_free(fs.first_m); 368 vm_page_unlock(fs.first_m); 369 vm_object_pip_wakeup(fs.first_object); 370 VM_OBJECT_WUNLOCK(fs.first_object); 371 fs.first_m = NULL; 372 } 373 unlock_map(&fs); 374 if (fs.m == vm_page_lookup(fs.object, 375 fs.pindex)) { 376 vm_page_sleep_if_busy(fs.m, "vmpfw"); 377 } 378 vm_object_pip_wakeup(fs.object); 379 VM_OBJECT_WUNLOCK(fs.object); 380 PCPU_INC(cnt.v_intrans); 381 vm_object_deallocate(fs.first_object); 382 goto RetryFault; 383 } 384 vm_page_lock(fs.m); 385 vm_page_remque(fs.m); 386 vm_page_unlock(fs.m); 387 388 /* 389 * Mark page busy for other processes, and the 390 * pagedaemon. If it still isn't completely valid 391 * (readable), jump to readrest, else break-out ( we 392 * found the page ). 393 */ 394 vm_page_xbusy(fs.m); 395 if (fs.m->valid != VM_PAGE_BITS_ALL) 396 goto readrest; 397 break; 398 } 399 400 /* 401 * Page is not resident, If this is the search termination 402 * or the pager might contain the page, allocate a new page. 403 */ 404 if (TRYPAGER || fs.object == fs.first_object) { 405 if (fs.pindex >= fs.object->size) { 406 unlock_and_deallocate(&fs); 407 return (KERN_PROTECTION_FAILURE); 408 } 409 410 /* 411 * Allocate a new page for this object/offset pair. 412 * 413 * Unlocked read of the p_flag is harmless. At 414 * worst, the P_KILLED might be not observed 415 * there, and allocation can fail, causing 416 * restart and new reading of the p_flag. 417 */ 418 fs.m = NULL; 419 if (!vm_page_count_severe() || P_KILLED(curproc)) { 420 #if VM_NRESERVLEVEL > 0 421 if ((fs.object->flags & OBJ_COLORED) == 0) { 422 fs.object->flags |= OBJ_COLORED; 423 fs.object->pg_color = atop(vaddr) - 424 fs.pindex; 425 } 426 #endif 427 alloc_req = P_KILLED(curproc) ? 428 VM_ALLOC_SYSTEM : VM_ALLOC_NORMAL; 429 if (fs.object->type != OBJT_VNODE && 430 fs.object->backing_object == NULL) 431 alloc_req |= VM_ALLOC_ZERO; 432 fs.m = vm_page_alloc(fs.object, fs.pindex, 433 alloc_req); 434 } 435 if (fs.m == NULL) { 436 unlock_and_deallocate(&fs); 437 VM_WAITPFAULT; 438 goto RetryFault; 439 } else if (fs.m->valid == VM_PAGE_BITS_ALL) 440 break; 441 } 442 443 readrest: 444 /* 445 * We have found a valid page or we have allocated a new page. 446 * The page thus may not be valid or may not be entirely 447 * valid. 448 * 449 * Attempt to fault-in the page if there is a chance that the 450 * pager has it, and potentially fault in additional pages 451 * at the same time. 452 */ 453 if (TRYPAGER) { 454 int rv; 455 u_char behavior = vm_map_entry_behavior(fs.entry); 456 457 if (behavior == MAP_ENTRY_BEHAV_RANDOM || 458 P_KILLED(curproc)) { 459 behind = 0; 460 ahead = 0; 461 } else if (behavior == MAP_ENTRY_BEHAV_SEQUENTIAL) { 462 behind = 0; 463 ahead = atop(fs.entry->end - vaddr) - 1; 464 if (ahead > VM_FAULT_READ_AHEAD_MAX) 465 ahead = VM_FAULT_READ_AHEAD_MAX; 466 if (fs.pindex == fs.entry->next_read) 467 vm_fault_cache_behind(&fs, 468 VM_FAULT_READ_MAX); 469 } else { 470 /* 471 * If this is a sequential page fault, then 472 * arithmetically increase the number of pages 473 * in the read-ahead window. Otherwise, reset 474 * the read-ahead window to its smallest size. 475 */ 476 behind = atop(vaddr - fs.entry->start); 477 if (behind > VM_FAULT_READ_BEHIND) 478 behind = VM_FAULT_READ_BEHIND; 479 ahead = atop(fs.entry->end - vaddr) - 1; 480 era = fs.entry->read_ahead; 481 if (fs.pindex == fs.entry->next_read) { 482 nera = era + behind; 483 if (nera > VM_FAULT_READ_AHEAD_MAX) 484 nera = VM_FAULT_READ_AHEAD_MAX; 485 behind = 0; 486 if (ahead > nera) 487 ahead = nera; 488 if (era == VM_FAULT_READ_AHEAD_MAX) 489 vm_fault_cache_behind(&fs, 490 VM_FAULT_CACHE_BEHIND); 491 } else if (ahead > VM_FAULT_READ_AHEAD_MIN) 492 ahead = VM_FAULT_READ_AHEAD_MIN; 493 if (era != ahead) 494 fs.entry->read_ahead = ahead; 495 } 496 497 /* 498 * Call the pager to retrieve the data, if any, after 499 * releasing the lock on the map. We hold a ref on 500 * fs.object and the pages are exclusive busied. 501 */ 502 unlock_map(&fs); 503 504 if (fs.object->type == OBJT_VNODE) { 505 vp = fs.object->handle; 506 if (vp == fs.vp) 507 goto vnode_locked; 508 else if (fs.vp != NULL) { 509 vput(fs.vp); 510 fs.vp = NULL; 511 } 512 locked = VOP_ISLOCKED(vp); 513 514 if (locked != LK_EXCLUSIVE) 515 locked = LK_SHARED; 516 /* Do not sleep for vnode lock while fs.m is busy */ 517 error = vget(vp, locked | LK_CANRECURSE | 518 LK_NOWAIT, curthread); 519 if (error != 0) { 520 vhold(vp); 521 release_page(&fs); 522 unlock_and_deallocate(&fs); 523 error = vget(vp, locked | LK_RETRY | 524 LK_CANRECURSE, curthread); 525 vdrop(vp); 526 fs.vp = vp; 527 KASSERT(error == 0, 528 ("vm_fault: vget failed")); 529 goto RetryFault; 530 } 531 fs.vp = vp; 532 } 533 vnode_locked: 534 KASSERT(fs.vp == NULL || !fs.map->system_map, 535 ("vm_fault: vnode-backed object mapped by system map")); 536 537 /* 538 * now we find out if any other pages should be paged 539 * in at this time this routine checks to see if the 540 * pages surrounding this fault reside in the same 541 * object as the page for this fault. If they do, 542 * then they are faulted in also into the object. The 543 * array "marray" returned contains an array of 544 * vm_page_t structs where one of them is the 545 * vm_page_t passed to the routine. The reqpage 546 * return value is the index into the marray for the 547 * vm_page_t passed to the routine. 548 * 549 * fs.m plus the additional pages are exclusive busied. 550 */ 551 faultcount = vm_fault_additional_pages( 552 fs.m, behind, ahead, marray, &reqpage); 553 554 rv = faultcount ? 555 vm_pager_get_pages(fs.object, marray, faultcount, 556 reqpage) : VM_PAGER_FAIL; 557 558 if (rv == VM_PAGER_OK) { 559 /* 560 * Found the page. Leave it busy while we play 561 * with it. 562 */ 563 564 /* 565 * Relookup in case pager changed page. Pager 566 * is responsible for disposition of old page 567 * if moved. 568 */ 569 fs.m = vm_page_lookup(fs.object, fs.pindex); 570 if (!fs.m) { 571 unlock_and_deallocate(&fs); 572 goto RetryFault; 573 } 574 575 hardfault++; 576 break; /* break to PAGE HAS BEEN FOUND */ 577 } 578 /* 579 * Remove the bogus page (which does not exist at this 580 * object/offset); before doing so, we must get back 581 * our object lock to preserve our invariant. 582 * 583 * Also wake up any other process that may want to bring 584 * in this page. 585 * 586 * If this is the top-level object, we must leave the 587 * busy page to prevent another process from rushing 588 * past us, and inserting the page in that object at 589 * the same time that we are. 590 */ 591 if (rv == VM_PAGER_ERROR) 592 printf("vm_fault: pager read error, pid %d (%s)\n", 593 curproc->p_pid, curproc->p_comm); 594 /* 595 * Data outside the range of the pager or an I/O error 596 */ 597 /* 598 * XXX - the check for kernel_map is a kludge to work 599 * around having the machine panic on a kernel space 600 * fault w/ I/O error. 601 */ 602 if (((fs.map != kernel_map) && (rv == VM_PAGER_ERROR)) || 603 (rv == VM_PAGER_BAD)) { 604 vm_page_lock(fs.m); 605 vm_page_free(fs.m); 606 vm_page_unlock(fs.m); 607 fs.m = NULL; 608 unlock_and_deallocate(&fs); 609 return ((rv == VM_PAGER_ERROR) ? KERN_FAILURE : KERN_PROTECTION_FAILURE); 610 } 611 if (fs.object != fs.first_object) { 612 vm_page_lock(fs.m); 613 vm_page_free(fs.m); 614 vm_page_unlock(fs.m); 615 fs.m = NULL; 616 /* 617 * XXX - we cannot just fall out at this 618 * point, m has been freed and is invalid! 619 */ 620 } 621 } 622 623 /* 624 * We get here if the object has default pager (or unwiring) 625 * or the pager doesn't have the page. 626 */ 627 if (fs.object == fs.first_object) 628 fs.first_m = fs.m; 629 630 /* 631 * Move on to the next object. Lock the next object before 632 * unlocking the current one. 633 */ 634 fs.pindex += OFF_TO_IDX(fs.object->backing_object_offset); 635 next_object = fs.object->backing_object; 636 if (next_object == NULL) { 637 /* 638 * If there's no object left, fill the page in the top 639 * object with zeros. 640 */ 641 if (fs.object != fs.first_object) { 642 vm_object_pip_wakeup(fs.object); 643 VM_OBJECT_WUNLOCK(fs.object); 644 645 fs.object = fs.first_object; 646 fs.pindex = fs.first_pindex; 647 fs.m = fs.first_m; 648 VM_OBJECT_WLOCK(fs.object); 649 } 650 fs.first_m = NULL; 651 652 /* 653 * Zero the page if necessary and mark it valid. 654 */ 655 if ((fs.m->flags & PG_ZERO) == 0) { 656 pmap_zero_page(fs.m); 657 } else { 658 PCPU_INC(cnt.v_ozfod); 659 } 660 PCPU_INC(cnt.v_zfod); 661 fs.m->valid = VM_PAGE_BITS_ALL; 662 break; /* break to PAGE HAS BEEN FOUND */ 663 } else { 664 KASSERT(fs.object != next_object, 665 ("object loop %p", next_object)); 666 VM_OBJECT_WLOCK(next_object); 667 vm_object_pip_add(next_object, 1); 668 if (fs.object != fs.first_object) 669 vm_object_pip_wakeup(fs.object); 670 VM_OBJECT_WUNLOCK(fs.object); 671 fs.object = next_object; 672 } 673 } 674 675 vm_page_assert_xbusied(fs.m); 676 677 /* 678 * PAGE HAS BEEN FOUND. [Loop invariant still holds -- the object lock 679 * is held.] 680 */ 681 682 /* 683 * If the page is being written, but isn't already owned by the 684 * top-level object, we have to copy it into a new page owned by the 685 * top-level object. 686 */ 687 if (fs.object != fs.first_object) { 688 /* 689 * We only really need to copy if we want to write it. 690 */ 691 if ((fault_type & (VM_PROT_COPY | VM_PROT_WRITE)) != 0) { 692 /* 693 * This allows pages to be virtually copied from a 694 * backing_object into the first_object, where the 695 * backing object has no other refs to it, and cannot 696 * gain any more refs. Instead of a bcopy, we just 697 * move the page from the backing object to the 698 * first object. Note that we must mark the page 699 * dirty in the first object so that it will go out 700 * to swap when needed. 701 */ 702 is_first_object_locked = FALSE; 703 if ( 704 /* 705 * Only one shadow object 706 */ 707 (fs.object->shadow_count == 1) && 708 /* 709 * No COW refs, except us 710 */ 711 (fs.object->ref_count == 1) && 712 /* 713 * No one else can look this object up 714 */ 715 (fs.object->handle == NULL) && 716 /* 717 * No other ways to look the object up 718 */ 719 ((fs.object->type == OBJT_DEFAULT) || 720 (fs.object->type == OBJT_SWAP)) && 721 (is_first_object_locked = VM_OBJECT_TRYWLOCK(fs.first_object)) && 722 /* 723 * We don't chase down the shadow chain 724 */ 725 fs.object == fs.first_object->backing_object) { 726 /* 727 * get rid of the unnecessary page 728 */ 729 vm_page_lock(fs.first_m); 730 vm_page_free(fs.first_m); 731 vm_page_unlock(fs.first_m); 732 /* 733 * grab the page and put it into the 734 * process'es object. The page is 735 * automatically made dirty. 736 */ 737 if (vm_page_rename(fs.m, fs.first_object, 738 fs.first_pindex)) { 739 unlock_and_deallocate(&fs); 740 goto RetryFault; 741 } 742 vm_page_xbusy(fs.m); 743 fs.first_m = fs.m; 744 fs.m = NULL; 745 PCPU_INC(cnt.v_cow_optim); 746 } else { 747 /* 748 * Oh, well, lets copy it. 749 */ 750 pmap_copy_page(fs.m, fs.first_m); 751 fs.first_m->valid = VM_PAGE_BITS_ALL; 752 if (wired && (fault_flags & 753 VM_FAULT_CHANGE_WIRING) == 0) { 754 vm_page_lock(fs.first_m); 755 vm_page_wire(fs.first_m); 756 vm_page_unlock(fs.first_m); 757 758 vm_page_lock(fs.m); 759 vm_page_unwire(fs.m, FALSE); 760 vm_page_unlock(fs.m); 761 } 762 /* 763 * We no longer need the old page or object. 764 */ 765 release_page(&fs); 766 } 767 /* 768 * fs.object != fs.first_object due to above 769 * conditional 770 */ 771 vm_object_pip_wakeup(fs.object); 772 VM_OBJECT_WUNLOCK(fs.object); 773 /* 774 * Only use the new page below... 775 */ 776 fs.object = fs.first_object; 777 fs.pindex = fs.first_pindex; 778 fs.m = fs.first_m; 779 if (!is_first_object_locked) 780 VM_OBJECT_WLOCK(fs.object); 781 PCPU_INC(cnt.v_cow_faults); 782 curthread->td_cow++; 783 } else { 784 prot &= ~VM_PROT_WRITE; 785 } 786 } 787 788 /* 789 * We must verify that the maps have not changed since our last 790 * lookup. 791 */ 792 if (!fs.lookup_still_valid) { 793 vm_object_t retry_object; 794 vm_pindex_t retry_pindex; 795 vm_prot_t retry_prot; 796 797 if (!vm_map_trylock_read(fs.map)) { 798 release_page(&fs); 799 unlock_and_deallocate(&fs); 800 goto RetryFault; 801 } 802 fs.lookup_still_valid = TRUE; 803 if (fs.map->timestamp != map_generation) { 804 result = vm_map_lookup_locked(&fs.map, vaddr, fault_type, 805 &fs.entry, &retry_object, &retry_pindex, &retry_prot, &wired); 806 807 /* 808 * If we don't need the page any longer, put it on the inactive 809 * list (the easiest thing to do here). If no one needs it, 810 * pageout will grab it eventually. 811 */ 812 if (result != KERN_SUCCESS) { 813 release_page(&fs); 814 unlock_and_deallocate(&fs); 815 816 /* 817 * If retry of map lookup would have blocked then 818 * retry fault from start. 819 */ 820 if (result == KERN_FAILURE) 821 goto RetryFault; 822 return (result); 823 } 824 if ((retry_object != fs.first_object) || 825 (retry_pindex != fs.first_pindex)) { 826 release_page(&fs); 827 unlock_and_deallocate(&fs); 828 goto RetryFault; 829 } 830 831 /* 832 * Check whether the protection has changed or the object has 833 * been copied while we left the map unlocked. Changing from 834 * read to write permission is OK - we leave the page 835 * write-protected, and catch the write fault. Changing from 836 * write to read permission means that we can't mark the page 837 * write-enabled after all. 838 */ 839 prot &= retry_prot; 840 } 841 } 842 /* 843 * If the page was filled by a pager, update the map entry's 844 * last read offset. Since the pager does not return the 845 * actual set of pages that it read, this update is based on 846 * the requested set. Typically, the requested and actual 847 * sets are the same. 848 * 849 * XXX The following assignment modifies the map 850 * without holding a write lock on it. 851 */ 852 if (hardfault) 853 fs.entry->next_read = fs.pindex + faultcount - reqpage; 854 855 if ((prot & VM_PROT_WRITE) != 0 || 856 (fault_flags & VM_FAULT_DIRTY) != 0) { 857 vm_object_set_writeable_dirty(fs.object); 858 859 /* 860 * If this is a NOSYNC mmap we do not want to set VPO_NOSYNC 861 * if the page is already dirty to prevent data written with 862 * the expectation of being synced from not being synced. 863 * Likewise if this entry does not request NOSYNC then make 864 * sure the page isn't marked NOSYNC. Applications sharing 865 * data should use the same flags to avoid ping ponging. 866 */ 867 if (fs.entry->eflags & MAP_ENTRY_NOSYNC) { 868 if (fs.m->dirty == 0) 869 fs.m->oflags |= VPO_NOSYNC; 870 } else { 871 fs.m->oflags &= ~VPO_NOSYNC; 872 } 873 874 /* 875 * If the fault is a write, we know that this page is being 876 * written NOW so dirty it explicitly to save on 877 * pmap_is_modified() calls later. 878 * 879 * Also tell the backing pager, if any, that it should remove 880 * any swap backing since the page is now dirty. 881 */ 882 if (((fault_type & VM_PROT_WRITE) != 0 && 883 (fault_flags & VM_FAULT_CHANGE_WIRING) == 0) || 884 (fault_flags & VM_FAULT_DIRTY) != 0) { 885 vm_page_dirty(fs.m); 886 vm_pager_page_unswapped(fs.m); 887 } 888 } 889 890 vm_page_assert_xbusied(fs.m); 891 892 /* 893 * Page must be completely valid or it is not fit to 894 * map into user space. vm_pager_get_pages() ensures this. 895 */ 896 KASSERT(fs.m->valid == VM_PAGE_BITS_ALL, 897 ("vm_fault: page %p partially invalid", fs.m)); 898 VM_OBJECT_WUNLOCK(fs.object); 899 900 /* 901 * Put this page into the physical map. We had to do the unlock above 902 * because pmap_enter() may sleep. We don't put the page 903 * back on the active queue until later so that the pageout daemon 904 * won't find it (yet). 905 */ 906 pmap_enter(fs.map->pmap, vaddr, fault_type, fs.m, prot, wired); 907 if ((fault_flags & VM_FAULT_CHANGE_WIRING) == 0 && wired == 0) 908 vm_fault_prefault(fs.map->pmap, vaddr, fs.entry); 909 VM_OBJECT_WLOCK(fs.object); 910 vm_page_lock(fs.m); 911 912 /* 913 * If the page is not wired down, then put it where the pageout daemon 914 * can find it. 915 */ 916 if (fault_flags & VM_FAULT_CHANGE_WIRING) { 917 if (wired) 918 vm_page_wire(fs.m); 919 else 920 vm_page_unwire(fs.m, 1); 921 } else 922 vm_page_activate(fs.m); 923 if (m_hold != NULL) { 924 *m_hold = fs.m; 925 vm_page_hold(fs.m); 926 } 927 vm_page_unlock(fs.m); 928 vm_page_xunbusy(fs.m); 929 930 /* 931 * Unlock everything, and return 932 */ 933 unlock_and_deallocate(&fs); 934 if (hardfault) { 935 PCPU_INC(cnt.v_io_faults); 936 curthread->td_ru.ru_majflt++; 937 } else 938 curthread->td_ru.ru_minflt++; 939 940 return (KERN_SUCCESS); 941 } 942 943 /* 944 * Speed up the reclamation of up to "distance" pages that precede the 945 * faulting pindex within the first object of the shadow chain. 946 */ 947 static void 948 vm_fault_cache_behind(const struct faultstate *fs, int distance) 949 { 950 vm_object_t first_object, object; 951 vm_page_t m, m_prev; 952 vm_pindex_t pindex; 953 954 object = fs->object; 955 VM_OBJECT_ASSERT_WLOCKED(object); 956 first_object = fs->first_object; 957 if (first_object != object) { 958 if (!VM_OBJECT_TRYWLOCK(first_object)) { 959 VM_OBJECT_WUNLOCK(object); 960 VM_OBJECT_WLOCK(first_object); 961 VM_OBJECT_WLOCK(object); 962 } 963 } 964 /* Neither fictitious nor unmanaged pages can be cached. */ 965 if ((first_object->flags & (OBJ_FICTITIOUS | OBJ_UNMANAGED)) == 0) { 966 if (fs->first_pindex < distance) 967 pindex = 0; 968 else 969 pindex = fs->first_pindex - distance; 970 if (pindex < OFF_TO_IDX(fs->entry->offset)) 971 pindex = OFF_TO_IDX(fs->entry->offset); 972 m = first_object != object ? fs->first_m : fs->m; 973 vm_page_assert_xbusied(m); 974 m_prev = vm_page_prev(m); 975 while ((m = m_prev) != NULL && m->pindex >= pindex && 976 m->valid == VM_PAGE_BITS_ALL) { 977 m_prev = vm_page_prev(m); 978 if (vm_page_busied(m)) 979 continue; 980 vm_page_lock(m); 981 if (m->hold_count == 0 && m->wire_count == 0) { 982 pmap_remove_all(m); 983 vm_page_aflag_clear(m, PGA_REFERENCED); 984 if (m->dirty != 0) 985 vm_page_deactivate(m); 986 else 987 vm_page_cache(m); 988 } 989 vm_page_unlock(m); 990 } 991 } 992 if (first_object != object) 993 VM_OBJECT_WUNLOCK(first_object); 994 } 995 996 /* 997 * vm_fault_prefault provides a quick way of clustering 998 * pagefaults into a processes address space. It is a "cousin" 999 * of vm_map_pmap_enter, except it runs at page fault time instead 1000 * of mmap time. 1001 */ 1002 static void 1003 vm_fault_prefault(pmap_t pmap, vm_offset_t addra, vm_map_entry_t entry) 1004 { 1005 int i; 1006 vm_offset_t addr, starta; 1007 vm_pindex_t pindex; 1008 vm_page_t m; 1009 vm_object_t object; 1010 1011 if (pmap != vmspace_pmap(curthread->td_proc->p_vmspace)) 1012 return; 1013 1014 object = entry->object.vm_object; 1015 1016 starta = addra - PFBAK * PAGE_SIZE; 1017 if (starta < entry->start) { 1018 starta = entry->start; 1019 } else if (starta > addra) { 1020 starta = 0; 1021 } 1022 1023 for (i = 0; i < PAGEORDER_SIZE; i++) { 1024 vm_object_t backing_object, lobject; 1025 1026 addr = addra + prefault_pageorder[i]; 1027 if (addr > addra + (PFFOR * PAGE_SIZE)) 1028 addr = 0; 1029 1030 if (addr < starta || addr >= entry->end) 1031 continue; 1032 1033 if (!pmap_is_prefaultable(pmap, addr)) 1034 continue; 1035 1036 pindex = ((addr - entry->start) + entry->offset) >> PAGE_SHIFT; 1037 lobject = object; 1038 VM_OBJECT_RLOCK(lobject); 1039 while ((m = vm_page_lookup(lobject, pindex)) == NULL && 1040 lobject->type == OBJT_DEFAULT && 1041 (backing_object = lobject->backing_object) != NULL) { 1042 KASSERT((lobject->backing_object_offset & PAGE_MASK) == 1043 0, ("vm_fault_prefault: unaligned object offset")); 1044 pindex += lobject->backing_object_offset >> PAGE_SHIFT; 1045 VM_OBJECT_RLOCK(backing_object); 1046 VM_OBJECT_RUNLOCK(lobject); 1047 lobject = backing_object; 1048 } 1049 /* 1050 * give-up when a page is not in memory 1051 */ 1052 if (m == NULL) { 1053 VM_OBJECT_RUNLOCK(lobject); 1054 break; 1055 } 1056 if (m->valid == VM_PAGE_BITS_ALL && 1057 (m->flags & PG_FICTITIOUS) == 0) 1058 pmap_enter_quick(pmap, addr, m, entry->protection); 1059 VM_OBJECT_RUNLOCK(lobject); 1060 } 1061 } 1062 1063 /* 1064 * Hold each of the physical pages that are mapped by the specified range of 1065 * virtual addresses, ["addr", "addr" + "len"), if those mappings are valid 1066 * and allow the specified types of access, "prot". If all of the implied 1067 * pages are successfully held, then the number of held pages is returned 1068 * together with pointers to those pages in the array "ma". However, if any 1069 * of the pages cannot be held, -1 is returned. 1070 */ 1071 int 1072 vm_fault_quick_hold_pages(vm_map_t map, vm_offset_t addr, vm_size_t len, 1073 vm_prot_t prot, vm_page_t *ma, int max_count) 1074 { 1075 vm_offset_t end, va; 1076 vm_page_t *mp; 1077 int count; 1078 boolean_t pmap_failed; 1079 1080 if (len == 0) 1081 return (0); 1082 end = round_page(addr + len); 1083 addr = trunc_page(addr); 1084 1085 /* 1086 * Check for illegal addresses. 1087 */ 1088 if (addr < vm_map_min(map) || addr > end || end > vm_map_max(map)) 1089 return (-1); 1090 1091 count = howmany(end - addr, PAGE_SIZE); 1092 if (count > max_count) 1093 panic("vm_fault_quick_hold_pages: count > max_count"); 1094 1095 /* 1096 * Most likely, the physical pages are resident in the pmap, so it is 1097 * faster to try pmap_extract_and_hold() first. 1098 */ 1099 pmap_failed = FALSE; 1100 for (mp = ma, va = addr; va < end; mp++, va += PAGE_SIZE) { 1101 *mp = pmap_extract_and_hold(map->pmap, va, prot); 1102 if (*mp == NULL) 1103 pmap_failed = TRUE; 1104 else if ((prot & VM_PROT_WRITE) != 0 && 1105 (*mp)->dirty != VM_PAGE_BITS_ALL) { 1106 /* 1107 * Explicitly dirty the physical page. Otherwise, the 1108 * caller's changes may go unnoticed because they are 1109 * performed through an unmanaged mapping or by a DMA 1110 * operation. 1111 * 1112 * The object lock is not held here. 1113 * See vm_page_clear_dirty_mask(). 1114 */ 1115 vm_page_dirty(*mp); 1116 } 1117 } 1118 if (pmap_failed) { 1119 /* 1120 * One or more pages could not be held by the pmap. Either no 1121 * page was mapped at the specified virtual address or that 1122 * mapping had insufficient permissions. Attempt to fault in 1123 * and hold these pages. 1124 */ 1125 for (mp = ma, va = addr; va < end; mp++, va += PAGE_SIZE) 1126 if (*mp == NULL && vm_fault_hold(map, va, prot, 1127 VM_FAULT_NORMAL, mp) != KERN_SUCCESS) 1128 goto error; 1129 } 1130 return (count); 1131 error: 1132 for (mp = ma; mp < ma + count; mp++) 1133 if (*mp != NULL) { 1134 vm_page_lock(*mp); 1135 vm_page_unhold(*mp); 1136 vm_page_unlock(*mp); 1137 } 1138 return (-1); 1139 } 1140 1141 /* 1142 * vm_fault_wire: 1143 * 1144 * Wire down a range of virtual addresses in a map. 1145 */ 1146 int 1147 vm_fault_wire(vm_map_t map, vm_offset_t start, vm_offset_t end, 1148 boolean_t fictitious) 1149 { 1150 vm_offset_t va; 1151 int rv; 1152 1153 /* 1154 * We simulate a fault to get the page and enter it in the physical 1155 * map. For user wiring, we only ask for read access on currently 1156 * read-only sections. 1157 */ 1158 for (va = start; va < end; va += PAGE_SIZE) { 1159 rv = vm_fault(map, va, VM_PROT_NONE, VM_FAULT_CHANGE_WIRING); 1160 if (rv) { 1161 if (va != start) 1162 vm_fault_unwire(map, start, va, fictitious); 1163 return (rv); 1164 } 1165 } 1166 return (KERN_SUCCESS); 1167 } 1168 1169 /* 1170 * vm_fault_unwire: 1171 * 1172 * Unwire a range of virtual addresses in a map. 1173 */ 1174 void 1175 vm_fault_unwire(vm_map_t map, vm_offset_t start, vm_offset_t end, 1176 boolean_t fictitious) 1177 { 1178 vm_paddr_t pa; 1179 vm_offset_t va; 1180 vm_page_t m; 1181 pmap_t pmap; 1182 1183 pmap = vm_map_pmap(map); 1184 1185 /* 1186 * Since the pages are wired down, we must be able to get their 1187 * mappings from the physical map system. 1188 */ 1189 for (va = start; va < end; va += PAGE_SIZE) { 1190 pa = pmap_extract(pmap, va); 1191 if (pa != 0) { 1192 pmap_change_wiring(pmap, va, FALSE); 1193 if (!fictitious) { 1194 m = PHYS_TO_VM_PAGE(pa); 1195 vm_page_lock(m); 1196 vm_page_unwire(m, TRUE); 1197 vm_page_unlock(m); 1198 } 1199 } 1200 } 1201 } 1202 1203 /* 1204 * Routine: 1205 * vm_fault_copy_entry 1206 * Function: 1207 * Create new shadow object backing dst_entry with private copy of 1208 * all underlying pages. When src_entry is equal to dst_entry, 1209 * function implements COW for wired-down map entry. Otherwise, 1210 * it forks wired entry into dst_map. 1211 * 1212 * In/out conditions: 1213 * The source and destination maps must be locked for write. 1214 * The source map entry must be wired down (or be a sharing map 1215 * entry corresponding to a main map entry that is wired down). 1216 */ 1217 void 1218 vm_fault_copy_entry(vm_map_t dst_map, vm_map_t src_map, 1219 vm_map_entry_t dst_entry, vm_map_entry_t src_entry, 1220 vm_ooffset_t *fork_charge) 1221 { 1222 vm_object_t backing_object, dst_object, object, src_object; 1223 vm_pindex_t dst_pindex, pindex, src_pindex; 1224 vm_prot_t access, prot; 1225 vm_offset_t vaddr; 1226 vm_page_t dst_m; 1227 vm_page_t src_m; 1228 boolean_t src_readonly, upgrade; 1229 1230 #ifdef lint 1231 src_map++; 1232 #endif /* lint */ 1233 1234 upgrade = src_entry == dst_entry; 1235 1236 src_object = src_entry->object.vm_object; 1237 src_pindex = OFF_TO_IDX(src_entry->offset); 1238 src_readonly = (src_entry->protection & VM_PROT_WRITE) == 0; 1239 1240 /* 1241 * Create the top-level object for the destination entry. (Doesn't 1242 * actually shadow anything - we copy the pages directly.) 1243 */ 1244 dst_object = vm_object_allocate(OBJT_DEFAULT, 1245 OFF_TO_IDX(dst_entry->end - dst_entry->start)); 1246 #if VM_NRESERVLEVEL > 0 1247 dst_object->flags |= OBJ_COLORED; 1248 dst_object->pg_color = atop(dst_entry->start); 1249 #endif 1250 1251 VM_OBJECT_WLOCK(dst_object); 1252 KASSERT(upgrade || dst_entry->object.vm_object == NULL, 1253 ("vm_fault_copy_entry: vm_object not NULL")); 1254 dst_entry->object.vm_object = dst_object; 1255 dst_entry->offset = 0; 1256 dst_object->charge = dst_entry->end - dst_entry->start; 1257 if (fork_charge != NULL) { 1258 KASSERT(dst_entry->cred == NULL, 1259 ("vm_fault_copy_entry: leaked swp charge")); 1260 dst_object->cred = curthread->td_ucred; 1261 crhold(dst_object->cred); 1262 *fork_charge += dst_object->charge; 1263 } else { 1264 dst_object->cred = dst_entry->cred; 1265 dst_entry->cred = NULL; 1266 } 1267 access = prot = dst_entry->protection; 1268 /* 1269 * If not an upgrade, then enter the mappings in the pmap as 1270 * read and/or execute accesses. Otherwise, enter them as 1271 * write accesses. 1272 * 1273 * A writeable large page mapping is only created if all of 1274 * the constituent small page mappings are modified. Marking 1275 * PTEs as modified on inception allows promotion to happen 1276 * without taking potentially large number of soft faults. 1277 */ 1278 if (!upgrade) 1279 access &= ~VM_PROT_WRITE; 1280 1281 /* 1282 * Loop through all of the virtual pages within the entry's 1283 * range, copying each page from the source object to the 1284 * destination object. Since the source is wired, those pages 1285 * must exist. In contrast, the destination is pageable. 1286 * Since the destination object does share any backing storage 1287 * with the source object, all of its pages must be dirtied, 1288 * regardless of whether they can be written. 1289 */ 1290 for (vaddr = dst_entry->start, dst_pindex = 0; 1291 vaddr < dst_entry->end; 1292 vaddr += PAGE_SIZE, dst_pindex++) { 1293 1294 /* 1295 * Allocate a page in the destination object. 1296 */ 1297 do { 1298 dst_m = vm_page_alloc(dst_object, dst_pindex, 1299 VM_ALLOC_NORMAL); 1300 if (dst_m == NULL) { 1301 VM_OBJECT_WUNLOCK(dst_object); 1302 VM_WAIT; 1303 VM_OBJECT_WLOCK(dst_object); 1304 } 1305 } while (dst_m == NULL); 1306 1307 /* 1308 * Find the page in the source object, and copy it in. 1309 * (Because the source is wired down, the page will be in 1310 * memory.) 1311 */ 1312 VM_OBJECT_RLOCK(src_object); 1313 object = src_object; 1314 pindex = src_pindex + dst_pindex; 1315 while ((src_m = vm_page_lookup(object, pindex)) == NULL && 1316 src_readonly && 1317 (backing_object = object->backing_object) != NULL) { 1318 /* 1319 * Allow fallback to backing objects if we are reading. 1320 */ 1321 VM_OBJECT_RLOCK(backing_object); 1322 pindex += OFF_TO_IDX(object->backing_object_offset); 1323 VM_OBJECT_RUNLOCK(object); 1324 object = backing_object; 1325 } 1326 if (src_m == NULL) 1327 panic("vm_fault_copy_wired: page missing"); 1328 pmap_copy_page(src_m, dst_m); 1329 VM_OBJECT_RUNLOCK(object); 1330 dst_m->valid = VM_PAGE_BITS_ALL; 1331 dst_m->dirty = VM_PAGE_BITS_ALL; 1332 VM_OBJECT_WUNLOCK(dst_object); 1333 1334 /* 1335 * Enter it in the pmap. If a wired, copy-on-write 1336 * mapping is being replaced by a write-enabled 1337 * mapping, then wire that new mapping. 1338 */ 1339 pmap_enter(dst_map->pmap, vaddr, access, dst_m, prot, upgrade); 1340 1341 /* 1342 * Mark it no longer busy, and put it on the active list. 1343 */ 1344 VM_OBJECT_WLOCK(dst_object); 1345 1346 if (upgrade) { 1347 vm_page_lock(src_m); 1348 vm_page_unwire(src_m, 0); 1349 vm_page_unlock(src_m); 1350 1351 vm_page_lock(dst_m); 1352 vm_page_wire(dst_m); 1353 vm_page_unlock(dst_m); 1354 } else { 1355 vm_page_lock(dst_m); 1356 vm_page_activate(dst_m); 1357 vm_page_unlock(dst_m); 1358 } 1359 vm_page_xunbusy(dst_m); 1360 } 1361 VM_OBJECT_WUNLOCK(dst_object); 1362 if (upgrade) { 1363 dst_entry->eflags &= ~(MAP_ENTRY_COW | MAP_ENTRY_NEEDS_COPY); 1364 vm_object_deallocate(src_object); 1365 } 1366 } 1367 1368 1369 /* 1370 * This routine checks around the requested page for other pages that 1371 * might be able to be faulted in. This routine brackets the viable 1372 * pages for the pages to be paged in. 1373 * 1374 * Inputs: 1375 * m, rbehind, rahead 1376 * 1377 * Outputs: 1378 * marray (array of vm_page_t), reqpage (index of requested page) 1379 * 1380 * Return value: 1381 * number of pages in marray 1382 */ 1383 static int 1384 vm_fault_additional_pages(m, rbehind, rahead, marray, reqpage) 1385 vm_page_t m; 1386 int rbehind; 1387 int rahead; 1388 vm_page_t *marray; 1389 int *reqpage; 1390 { 1391 int i,j; 1392 vm_object_t object; 1393 vm_pindex_t pindex, startpindex, endpindex, tpindex; 1394 vm_page_t rtm; 1395 int cbehind, cahead; 1396 1397 VM_OBJECT_ASSERT_WLOCKED(m->object); 1398 1399 object = m->object; 1400 pindex = m->pindex; 1401 cbehind = cahead = 0; 1402 1403 /* 1404 * if the requested page is not available, then give up now 1405 */ 1406 if (!vm_pager_has_page(object, pindex, &cbehind, &cahead)) { 1407 return 0; 1408 } 1409 1410 if ((cbehind == 0) && (cahead == 0)) { 1411 *reqpage = 0; 1412 marray[0] = m; 1413 return 1; 1414 } 1415 1416 if (rahead > cahead) { 1417 rahead = cahead; 1418 } 1419 1420 if (rbehind > cbehind) { 1421 rbehind = cbehind; 1422 } 1423 1424 /* 1425 * scan backward for the read behind pages -- in memory 1426 */ 1427 if (pindex > 0) { 1428 if (rbehind > pindex) { 1429 rbehind = pindex; 1430 startpindex = 0; 1431 } else { 1432 startpindex = pindex - rbehind; 1433 } 1434 1435 if ((rtm = TAILQ_PREV(m, pglist, listq)) != NULL && 1436 rtm->pindex >= startpindex) 1437 startpindex = rtm->pindex + 1; 1438 1439 /* tpindex is unsigned; beware of numeric underflow. */ 1440 for (i = 0, tpindex = pindex - 1; tpindex >= startpindex && 1441 tpindex < pindex; i++, tpindex--) { 1442 1443 rtm = vm_page_alloc(object, tpindex, VM_ALLOC_NORMAL | 1444 VM_ALLOC_IFNOTCACHED); 1445 if (rtm == NULL) { 1446 /* 1447 * Shift the allocated pages to the 1448 * beginning of the array. 1449 */ 1450 for (j = 0; j < i; j++) { 1451 marray[j] = marray[j + tpindex + 1 - 1452 startpindex]; 1453 } 1454 break; 1455 } 1456 1457 marray[tpindex - startpindex] = rtm; 1458 } 1459 } else { 1460 startpindex = 0; 1461 i = 0; 1462 } 1463 1464 marray[i] = m; 1465 /* page offset of the required page */ 1466 *reqpage = i; 1467 1468 tpindex = pindex + 1; 1469 i++; 1470 1471 /* 1472 * scan forward for the read ahead pages 1473 */ 1474 endpindex = tpindex + rahead; 1475 if ((rtm = TAILQ_NEXT(m, listq)) != NULL && rtm->pindex < endpindex) 1476 endpindex = rtm->pindex; 1477 if (endpindex > object->size) 1478 endpindex = object->size; 1479 1480 for (; tpindex < endpindex; i++, tpindex++) { 1481 1482 rtm = vm_page_alloc(object, tpindex, VM_ALLOC_NORMAL | 1483 VM_ALLOC_IFNOTCACHED); 1484 if (rtm == NULL) { 1485 break; 1486 } 1487 1488 marray[i] = rtm; 1489 } 1490 1491 /* return number of pages */ 1492 return i; 1493 } 1494 1495 /* 1496 * Block entry into the machine-independent layer's page fault handler by 1497 * the calling thread. Subsequent calls to vm_fault() by that thread will 1498 * return KERN_PROTECTION_FAILURE. Enable machine-dependent handling of 1499 * spurious page faults. 1500 */ 1501 int 1502 vm_fault_disable_pagefaults(void) 1503 { 1504 1505 return (curthread_pflags_set(TDP_NOFAULTING | TDP_RESETSPUR)); 1506 } 1507 1508 void 1509 vm_fault_enable_pagefaults(int save) 1510 { 1511 1512 curthread_pflags_restore(save); 1513 }
Cache object: ca65ab5a4263126322924e3d00e83e5b
[ source navigation ] [ diff markup ] [ identifier search ] [ freetext search ] [ file search ] [ list types ] [ track identifier ]